Now only Venetia and Rome was to be added to make the unification of Italy complete. For the attainment of the objective Victor Emmanuel II concluded a treaty with Bismarck whereby Italy agreed to invade Venetia, while Prussia was in­volved in a war against Austria. Obviously the purpose of the treaty was to divert the attention of Austria.

Accordingly, in 1866 when the war between Austria and Prussia broke out the Emperor of Italy also declared a war against Austria and invaded Tyrol, as well as Venetia. However, Italian forces failed to achieve any success. On the other hand, Prussia succeeded in scoring a victory over Austria. In terms of the treaty Bismarck handed over Venetia to Italy.